fs/open.c

   1 /*
   2  *  linux/fs/open.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/string.h>
   8 #include <linux/mm.h>
   9 #include <linux/file.h>
  10 #include <linux/fdtable.h>
  11 #include <linux/fsnotify.h>
  12 #include <linux/module.h>
  13 #include <linux/tty.h>
  14 #include <linux/namei.h>
  15 #include <linux/backing-dev.h>
  16 #include <linux/capability.h>
  17 #include <linux/securebits.h>
  18 #include <linux/security.h>
  19 #include <linux/mount.h>
  20 #include <linux/vfs.h>
  21 #include <linux/fcntl.h>
  22 #include <linux/slab.h>
  23 #include <asm/uaccess.h>
  24 #include <linux/fs.h>
  25 #include <linux/personality.h>
  26 #include <linux/pagemap.h>
  27 #include <linux/syscalls.h>
  28 #include <linux/rcupdate.h>
  29 #include <linux/audit.h>
  30 #include <linux/falloc.h>
  31 #include <linux/fs_struct.h>
  32 #include <linux/ima.h>
  33
  34 #include "internal.h"
  35
  36 int vfs_statfs(struct dentry *dentry, struct kstatfs *buf)
  37 {
  38         int retval = -ENODEV;
  39
  40         if (dentry) {
  41                 retval = -ENOSYS;
  42                 if (dentry->d_sb->s_op->statfs) {
  43                         memset(buf, 0, sizeof(*buf));
  44                         retval = security_sb_statfs(dentry);
  45                         if (retval)
  46                                 return retval;
  47                         retval = dentry->d_sb->s_op->statfs(dentry, buf);
  48                         if (retval == 0 && buf->f_frsize == 0)
  49                                 buf->f_frsize = buf->f_bsize;
  50                 }
  51         }
  52         return retval;
  53 }
  54
  55 EXPORT_SYMBOL(vfs_statfs);
  56
  57 static int vfs_statfs_native(struct dentry *dentry, struct statfs *buf)
  58 {
  59         struct kstatfs st;
  60         int retval;
  61
  62         retval = vfs_statfs(dentry, &st);
  63         if (retval)
  64                 return retval;
  65
  66         if (sizeof(*buf) == sizeof(st))
  67                 memcpy(buf, &st, sizeof(st));
  68         else {
  69                 if (sizeof buf->f_blocks == 4) {
  70                         if ((st.f_blocks | st.f_bfree | st.f_bavail |
  71                              st.f_bsize | st.f_frsize) &
  72                             0xffffffff00000000ULL)
  73                                 return -EOVERFLOW;
  74                         /*
  75                          * f_files and f_ffree may be -1; it's okay to stuff
  76                          * that into 32 bits
  77                          */
  78                         if (st.f_files != -1 &&
  79                             (st.f_files & 0xffffffff00000000ULL))
  80                                 return -EOVERFLOW;
  81                         if (st.f_ffree != -1 &&
  82                             (st.f_ffree & 0xffffffff00000000ULL))
  83                                 return -EOVERFLOW;
  84                 }
  85
  86                 buf->f_type = st.f_type;
  87                 buf->f_bsize = st.f_bsize;
  88                 buf->f_blocks = st.f_blocks;
  89                 buf->f_bfree = st.f_bfree;
  90                 buf->f_bavail = st.f_bavail;
  91                 buf->f_files = st.f_files;
  92                 buf->f_ffree = st.f_ffree;
  93                 buf->f_fsid = st.f_fsid;
  94                 buf->f_namelen = st.f_namelen;
  95                 buf->f_frsize = st.f_frsize;
  96                 memset(buf->f_spare, 0, sizeof(buf->f_spare));
  97         }
  98         return 0;
  99 }
 100
 101 static int vfs_statfs64(struct dentry *dentry, struct statfs64 *buf)
 102 {
 103         struct kstatfs st;
 104         int retval;
 105
 106         retval = vfs_statfs(dentry, &st);
 107         if (retval)
 108                 return retval;
 109
 110         if (sizeof(*buf) == sizeof(st))
 111                 memcpy(buf, &st, sizeof(st));
 112         else {
 113                 buf->f_type = st.f_type;
 114                 buf->f_bsize = st.f_bsize;
 115                 buf->f_blocks = st.f_blocks;
 116                 buf->f_bfree = st.f_bfree;
 117                 buf->f_bavail = st.f_bavail;
 118                 buf->f_files = st.f_files;
 119                 buf->f_ffree = st.f_ffree;
 120                 buf->f_fsid = st.f_fsid;
 121                 buf->f_namelen = st.f_namelen;
 122                 buf->f_frsize = st.f_frsize;
 123                 memset(buf->f_spare, 0, sizeof(buf->f_spare));
 124         }
 125         return 0;
 126 }
 127
 128 SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
 129 {
 130         struct path path;
 131         int error;
 132
 133         error = user_path(pathname, &path);
 134         if (!error) {
 135                 struct statfs tmp;
 136                 error = vfs_statfs_native(path.dentry, &tmp);
 137                 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
 138                         error = -EFAULT;
 139                 path_put(&path);
 140         }
 141         return error;
 142 }
 143
 144 SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
 145 {
 146         struct path path;
 147         long error;
 148
 149         if (sz != sizeof(*buf))
 150                 return -EINVAL;
 151         error = user_path(pathname, &path);
 152         if (!error) {
 153                 struct statfs64 tmp;
 154                 error = vfs_statfs64(path.dentry, &tmp);
 155                 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
 156                         error = -EFAULT;
 157                 path_put(&path);
 158         }
 159         return error;
 160 }
 161
 162 SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
 163 {
 164         struct file * file;
 165         struct statfs tmp;
 166         int error;
 167
 168         error = -EBADF;
 169         file = fget(fd);
 170         if (!file)
 171                 goto out;
 172         error = vfs_statfs_native(file->f_path.dentry, &tmp);
 173         if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
 174                 error = -EFAULT;
 175         fput(file);
 176 out:
 177         return error;
 178 }
 179
 180 SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
 181 {
 182         struct file * file;
 183         struct statfs64 tmp;
 184         int error;
 185
 186         if (sz != sizeof(*buf))
 187                 return -EINVAL;
 188
 189         error = -EBADF;
 190         file = fget(fd);
 191         if (!file)
 192                 goto out;
 193         error = vfs_statfs64(file->f_path.dentry, &tmp);
 194         if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
 195                 error = -EFAULT;
 196         fput(file);
 197 out:
 198         return error;
 199 }
 200
 201 int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
 202         struct file *filp)
 203 {
 204         int ret;
 205         struct iattr newattrs;
 206
 207         /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
 208         if (length < 0)
 209                 return -EINVAL;
 210
 211         newattrs.ia_size = length;
 212         newattrs.ia_valid = ATTR_SIZE | time_attrs;
 213         if (filp) {
 214                 newattrs.ia_file = filp;
 215                 newattrs.ia_valid |= ATTR_FILE;
 216         }
 217
 218         /* Remove suid/sgid on truncate too */
 219         ret = should_remove_suid(dentry);
 220         if (ret)
 221                 newattrs.ia_valid |= ret | ATTR_FORCE;
 222
 223         mutex_lock(&dentry->d_inode->i_mutex);
 224         ret = notify_change(dentry, &newattrs);
 225         mutex_unlock(&dentry->d_inode->i_mutex);
 226         return ret;
 227 }
 228
 229 static long do_sys_truncate(const char __user *pathname, loff_t length)
 230 {
 231         struct path path;
 232         struct inode *inode;
 233         int error;
 234
 235         error = -EINVAL;
 236         if (length < 0) /* sorry, but loff_t says... */
 237                 goto out;
 238
 239         error = user_path(pathname, &path);
 240         if (error)
 241                 goto out;
 242         inode = path.dentry->d_inode;
 243
 244         /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
 245         error = -EISDIR;
 246         if (S_ISDIR(inode->i_mode))
 247                 goto dput_and_out;
 248
 249         error = -EINVAL;
 250         if (!S_ISREG(inode->i_mode))
 251                 goto dput_and_out;
 252
 253         error = mnt_want_write(path.mnt);
 254         if (error)
 255                 goto dput_and_out;
 256
 257         error = inode_permission(inode, MAY_WRITE);
 258         if (error)
 259                 goto mnt_drop_write_and_out;
 260
 261         error = -EPERM;
 262         if (IS_APPEND(inode))
 263                 goto mnt_drop_write_and_out;
 264
 265         error = get_write_access(inode);
 266         if (error)
 267                 goto mnt_drop_write_and_out;
 268
 269         /*
 270          * Make sure that there are no leases.  get_write_access() protects
 271          * against the truncate racing with a lease-granting setlease().
 272          */
 273         error = break_lease(inode, O_WRONLY);
 274         if (error)
 275                 goto put_write_and_out;
 276
 277         error = locks_verify_truncate(inode, NULL, length);
 278         if (!error)
 279                 error = security_path_truncate(&path, length, 0);
 280         if (!error)
 281                 error = do_truncate(path.dentry, length, 0, NULL);
 282
 283 put_write_and_out:
 284         put_write_access(inode);
 285 mnt_drop_write_and_out:
 286         mnt_drop_write(path.mnt);
 287 dput_and_out:
 288         path_put(&path);
 289 out:
 290         return error;
 291 }
 292
 293 SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
 294 {
 295         return do_sys_truncate(path, length);
 296 }
 297
 298 static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
 299 {
 300         struct inode * inode;
 301         struct dentry *dentry;
 302         struct file * file;
 303         int error;
 304
 305         error = -EINVAL;
 306         if (length < 0)
 307                 goto out;
 308         error = -EBADF;
 309         file = fget(fd);
 310         if (!file)
 311                 goto out;
 312
 313         /* explicitly opened as large or we are on 64-bit box */
 314         if (file->f_flags & O_LARGEFILE)
 315                 small = 0;
 316
 317         dentry = file->f_path.dentry;
 318         inode = dentry->d_inode;
 319         error = -EINVAL;
 320         if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
 321                 goto out_putf;
 322
 323         error = -EINVAL;
 324         /* Cannot ftruncate over 2^31 bytes without large file support */
 325         if (small && length > MAX_NON_LFS)
 326                 goto out_putf;
 327
 328         error = -EPERM;
 329         if (IS_APPEND(inode))
 330                 goto out_putf;
 331
 332         error = locks_verify_truncate(inode, file, length);
 333         if (!error)
 334                 error = security_path_truncate(&file->f_path, length,
 335                                                ATTR_MTIME|ATTR_CTIME);
 336         if (!error)
 337                 error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
 338 out_putf:
 339         fput(file);
 340 out:
 341         return error;
 342 }
 343
 344 SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
 345 {
 346         long ret = do_sys_ftruncate(fd, length, 1);
 347         /* avoid REGPARM breakage on x86: */
 348         asmlinkage_protect(2, ret, fd, length);
 349         return ret;
 350 }
 351
 352 /* LFS versions of truncate are only needed on 32 bit machines */
 353 #if BITS_PER_LONG == 32
 354 SYSCALL_DEFINE(truncate64)(const char __user * path, loff_t length)
 355 {
 356         return do_sys_truncate(path, length);
 357 }
 358 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 359 asmlinkage long SyS_truncate64(long path, loff_t length)
 360 {
 361         return SYSC_truncate64((const char __user *) path, length);
 362 }
 363 SYSCALL_ALIAS(sys_truncate64, SyS_truncate64);
 364 #endif
 365
 366 SYSCALL_DEFINE(ftruncate64)(unsigned int fd, loff_t length)
 367 {
 368         long ret = do_sys_ftruncate(fd, length, 0);
 369         /* avoid REGPARM breakage on x86: */
 370         asmlinkage_protect(2, ret, fd, length);
 371         return ret;
 372 }
 373 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 374 asmlinkage long SyS_ftruncate64(long fd, loff_t length)
 375 {
 376         return SYSC_ftruncate64((unsigned int) fd, length);
 377 }
 378 SYSCALL_ALIAS(sys_ftruncate64, SyS_ftruncate64);
 379 #endif
 380 #endif /* BITS_PER_LONG == 32 */
 381
 382
 383 int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 384 {
 385         struct inode *inode = file->f_path.dentry->d_inode;
 386         long ret;
 387
 388         if (offset < 0 || len <= 0)
 389                 return -EINVAL;
 390
 391         /* Return error if mode is not supported */
 392         if (mode && !(mode & FALLOC_FL_KEEP_SIZE))
 393                 return -EOPNOTSUPP;
 394
 395         if (!(file->f_mode & FMODE_WRITE))
 396                 return -EBADF;
 397         /*
 398          * Revalidate the write permissions, in case security policy has
 399          * changed since the files were opened.
 400          */
 401         ret = security_file_permission(file, MAY_WRITE);
 402         if (ret)
 403                 return ret;
 404
 405         if (S_ISFIFO(inode->i_mode))
 406                 return -ESPIPE;
 407
 408         /*
 409          * Let individual file system decide if it supports preallocation
 410          * for directories or not.
 411          */
 412         if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
 413                 return -ENODEV;
 414
 415         /* Check for wrap through zero too */
 416         if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
 417                 return -EFBIG;
 418
 419         if (!inode->i_op->fallocate)
 420                 return -EOPNOTSUPP;
 421
 422         return inode->i_op->fallocate(inode, mode, offset, len);
 423 }
 424
 425 SYSCALL_DEFINE(fallocate)(int fd, int mode, loff_t offset, loff_t len)
 426 {
 427         struct file *file;
 428         int error = -EBADF;
 429
 430         file = fget(fd);
 431         if (file) {
 432                 error = do_fallocate(file, mode, offset, len);
 433                 fput(file);
 434         }
 435
 436         return error;
 437 }
 438
 439 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 440 asmlinkage long SyS_fallocate(long fd, long mode, loff_t offset, loff_t len)
 441 {
 442         return SYSC_fallocate((int)fd, (int)mode, offset, len);
 443 }
 444 SYSCALL_ALIAS(sys_fallocate, SyS_fallocate);
 445 #endif
 446
 447 /*
 448  * access() needs to use the real uid/gid, not the effective uid/gid.
 449  * We do this by temporarily clearing all FS-related capabilities and
 450  * switching the fsuid/fsgid around to the real ones.
 451  */
 452 SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
 453 {
 454         const struct cred *old_cred;
 455         struct cred *override_cred;
 456         struct path path;
 457         struct inode *inode;
 458         int res;
 459
 460         if (mode & ~S_IRWXO)    /* where's F_OK, X_OK, W_OK, R_OK? */
 461                 return -EINVAL;
 462
 463         override_cred = prepare_creds();
 464         if (!override_cred)
 465                 return -ENOMEM;
 466
 467         override_cred->fsuid = override_cred->uid;
 468         override_cred->fsgid = override_cred->gid;
 469
 470         if (!issecure(SECURE_NO_SETUID_FIXUP)) {
 471                 /* Clear the capabilities if we switch to a non-root user */
 472                 if (override_cred->uid)
 473                         cap_clear(override_cred->cap_effective);
 474                 else
 475                         override_cred->cap_effective =
 476                                 override_cred->cap_permitted;
 477         }
 478
 479         old_cred = override_creds(override_cred);
 480
 481         res = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
 482         if (res)
 483                 goto out;
 484
 485         inode = path.dentry->d_inode;
 486
 487         if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
 488                 /*
 489                  * MAY_EXEC on regular files is denied if the fs is mounted
 490                  * with the "noexec" flag.
 491                  */
 492                 res = -EACCES;
 493                 if (path.mnt->mnt_flags & MNT_NOEXEC)
 494                         goto out_path_release;
 495         }
 496
 497         res = inode_permission(inode, mode | MAY_ACCESS);
 498         /* SuS v2 requires we report a read only fs too */
 499         if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
 500                 goto out_path_release;
 501         /*
 502          * This is a rare case where using __mnt_is_readonly()
 503          * is OK without a mnt_want/drop_write() pair.  Since
 504          * no actual write to the fs is performed here, we do
 505          * not need to telegraph to that to anyone.
 506          *
 507          * By doing this, we accept that this access is
 508          * inherently racy and know that the fs may change
 509          * state before we even see this result.
 510          */
 511         if (__mnt_is_readonly(path.mnt))
 512                 res = -EROFS;
 513
 514 out_path_release:
 515         path_put(&path);
 516 out:
 517         revert_creds(old_cred);
 518         put_cred(override_cred);
 519         return res;
 520 }
 521
 522 SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
 523 {
 524         return sys_faccessat(AT_FDCWD, filename, mode);
 525 }
 526
 527 SYSCALL_DEFINE1(chdir, const char __user *, filename)
 528 {
 529         struct path path;
 530         int error;
 531
 532         error = user_path_dir(filename, &path);
 533         if (error)
 534                 goto out;
 535
 536         error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_ACCESS);
 537         if (error)
 538                 goto dput_and_out;
 539
 540         set_fs_pwd(current->fs, &path);
 541
 542 dput_and_out:
 543         path_put(&path);
 544 out:
 545         return error;
 546 }
 547
 548 SYSCALL_DEFINE1(fchdir, unsigned int, fd)
 549 {
 550         struct file *file;
 551         struct inode *inode;
 552         int error;
 553
 554         error = -EBADF;
 555         file = fget(fd);
 556         if (!file)
 557                 goto out;
 558
 559         inode = file->f_path.dentry->d_inode;
 560
 561         error = -ENOTDIR;
 562         if (!S_ISDIR(inode->i_mode))
 563                 goto out_putf;
 564
 565         error = inode_permission(inode, MAY_EXEC | MAY_ACCESS);
 566         if (!error)
 567                 set_fs_pwd(current->fs, &file->f_path);
 568 out_putf:
 569         fput(file);
 570 out:
 571         return error;
 572 }
 573
 574 SYSCALL_DEFINE1(chroot, const char __user *, filename)
 575 {
 576         struct path path;
 577         int error;
 578
 579         error = user_path_dir(filename, &path);
 580         if (error)
 581                 goto out;
 582
 583         error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_ACCESS);
 584         if (error)
 585                 goto dput_and_out;
 586
 587         error = -EPERM;
 588         if (!capable(CAP_SYS_CHROOT))
 589                 goto dput_and_out;
 590         error = security_path_chroot(&path);
 591         if (error)
 592                 goto dput_and_out;
 593
 594         set_fs_root(current->fs, &path);
 595         error = 0;
 596 dput_and_out:
 597         path_put(&path);
 598 out:
 599         return error;
 600 }
 601
 602 SYSCALL_DEFINE2(fchmod, unsigned int, fd, mode_t, mode)
 603 {
 604         struct inode * inode;
 605         struct dentry * dentry;
 606         struct file * file;
 607         int err = -EBADF;
 608         struct iattr newattrs;
 609
 610         file = fget(fd);
 611         if (!file)
 612                 goto out;
 613
 614         dentry = file->f_path.dentry;
 615         inode = dentry->d_inode;
 616
 617         audit_inode(NULL, dentry);
 618
 619         err = mnt_want_write_file(file);
 620         if (err)
 621                 goto out_putf;
 622         mutex_lock(&inode->i_mutex);
 623         err = security_path_chmod(dentry, file->f_vfsmnt, mode);
 624         if (err)
 625                 goto out_unlock;
 626         if (mode == (mode_t) -1)
 627                 mode = inode->i_mode;
 628         newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 629         newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 630         err = notify_change(dentry, &newattrs);
 631 out_unlock:
 632         mutex_unlock(&inode->i_mutex);
 633         mnt_drop_write(file->f_path.mnt);
 634 out_putf:
 635         fput(file);
 636 out:
 637         return err;
 638 }
 639
 640 SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, mode_t, mode)
 641 {
 642         struct path path;
 643         struct inode *inode;
 644         int error;
 645         struct iattr newattrs;
 646
 647         error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
 648         if (error)
 649                 goto out;
 650         inode = path.dentry->d_inode;
 651
 652         error = mnt_want_write(path.mnt);
 653         if (error)
 654                 goto dput_and_out;
 655         mutex_lock(&inode->i_mutex);
 656         error = security_path_chmod(path.dentry, path.mnt, mode);
 657         if (error)
 658                 goto out_unlock;
 659         if (mode == (mode_t) -1)
 660                 mode = inode->i_mode;
 661         newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 662         newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 663         error = notify_change(path.dentry, &newattrs);
 664 out_unlock:
 665         mutex_unlock(&inode->i_mutex);
 666         mnt_drop_write(path.mnt);
 667 dput_and_out:
 668         path_put(&path);
 669 out:
 670         return error;
 671 }
 672
 673 SYSCALL_DEFINE2(chmod, const char __user *, filename, mode_t, mode)
 674 {
 675         return sys_fchmodat(AT_FDCWD, filename, mode);
 676 }
 677
 678 static int chown_common(struct path *path, uid_t user, gid_t group)
 679 {
 680         struct inode *inode = path->dentry->d_inode;
 681         int error;
 682         struct iattr newattrs;
 683
 684         newattrs.ia_valid =  ATTR_CTIME;
 685         if (user != (uid_t) -1) {
 686                 newattrs.ia_valid |= ATTR_UID;
 687                 newattrs.ia_uid = user;
 688         }
 689         if (group != (gid_t) -1) {
 690                 newattrs.ia_valid |= ATTR_GID;
 691                 newattrs.ia_gid = group;
 692         }
 693         if (!S_ISDIR(inode->i_mode))
 694                 newattrs.ia_valid |=
 695                         ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
 696         mutex_lock(&inode->i_mutex);
 697         error = security_path_chown(path, user, group);
 698         if (!error)
 699                 error = notify_change(path->dentry, &newattrs);
 700         mutex_unlock(&inode->i_mutex);
 701
 702         return error;
 703 }
 704
 705 SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
 706 {
 707         struct path path;
 708         int error;
 709
 710         error = user_path(filename, &path);
 711         if (error)
 712                 goto out;
 713         error = mnt_want_write(path.mnt);
 714         if (error)
 715                 goto out_release;
 716         error = chown_common(&path, user, group);
 717         mnt_drop_write(path.mnt);
 718 out_release:
 719         path_put(&path);
 720 out:
 721         return error;
 722 }
 723
 724 SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
 725                 gid_t, group, int, flag)
 726 {
 727         struct path path;
 728         int error = -EINVAL;
 729         int follow;
 730
 731         if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
 732                 goto out;
 733
 734         follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
 735         error = user_path_at(dfd, filename, follow, &path);
 736         if (error)
 737                 goto out;
 738         error = mnt_want_write(path.mnt);
 739         if (error)
 740                 goto out_release;
 741         error = chown_common(&path, user, group);
 742         mnt_drop_write(path.mnt);
 743 out_release:
 744         path_put(&path);
 745 out:
 746         return error;
 747 }
 748
 749 SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
 750 {
 751         struct path path;
 752         int error;
 753
 754         error = user_lpath(filename, &path);
 755         if (error)
 756                 goto out;
 757         error = mnt_want_write(path.mnt);
 758         if (error)
 759                 goto out_release;
 760         error = chown_common(&path, user, group);
 761         mnt_drop_write(path.mnt);
 762 out_release:
 763         path_put(&path);
 764 out:
 765         return error;
 766 }
 767
 768 SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
 769 {
 770         struct file * file;
 771         int error = -EBADF;
 772         struct dentry * dentry;
 773
 774         file = fget(fd);
 775         if (!file)
 776                 goto out;
 777
 778         error = mnt_want_write_file(file);
 779         if (error)
 780                 goto out_fput;
 781         dentry = file->f_path.dentry;
 782         audit_inode(NULL, dentry);
 783         error = chown_common(&file->f_path, user, group);
 784         mnt_drop_write(file->f_path.mnt);
 785 out_fput:
 786         fput(file);
 787 out:
 788         return error;
 789 }
 790
 791 /*
 792  * You have to be very careful that these write
 793  * counts get cleaned up in error cases and
 794  * upon __fput().  This should probably never
 795  * be called outside of __dentry_open().
 796  */
 797 static inline int __get_file_write_access(struct inode *inode,
 798                                           struct vfsmount *mnt)
 799 {
 800         int error;
 801         error = get_write_access(inode);
 802         if (error)
 803                 return error;
 804         /*
 805          * Do not take mount writer counts on
 806          * special files since no writes to
 807          * the mount itself will occur.
 808          */
 809         if (!special_file(inode->i_mode)) {
 810                 /*
 811                  * Balanced in __fput()
 812                  */
 813                 error = mnt_want_write(mnt);
 814                 if (error)
 815                         put_write_access(inode);
 816         }
 817         return error;
 818 }
 819
 820 static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
 821                                         struct file *f,
 822                                         int (*open)(struct inode *, struct file *),
 823                                         const struct cred *cred)
 824 {
 825         struct inode *inode;
 826         int error;
 827
 828         f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
 829                                 FMODE_PREAD | FMODE_PWRITE;
 830         inode = dentry->d_inode;
 831         if (f->f_mode & FMODE_WRITE) {
 832                 error = __get_file_write_access(inode, mnt);
 833                 if (error)
 834                         goto cleanup_file;
 835                 if (!special_file(inode->i_mode))
 836                         file_take_write(f);
 837         }
 838
 839         f->f_mapping = inode->i_mapping;
 840         f->f_path.dentry = dentry;
 841         f->f_path.mnt = mnt;
 842         f->f_pos = 0;
 843         f->f_op = fops_get(inode->i_fop);
 844         file_move(f, &inode->i_sb->s_files);
 845
 846         error = security_dentry_open(f, cred);
 847         if (error)
 848                 goto cleanup_all;
 849
 850         if (!open && f->f_op)
 851                 open = f->f_op->open;
 852         if (open) {
 853                 error = open(inode, f);
 854                 if (error)
 855                         goto cleanup_all;
 856         }
 857         ima_counts_get(f);
 858
 859         f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 860
 861         file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
 862
 863         /* NB: we're sure to have correct a_ops only after f_op->open */
 864         if (f->f_flags & O_DIRECT) {
 865                 if (!f->f_mapping->a_ops ||
 866                     ((!f->f_mapping->a_ops->direct_IO) &&
 867                     (!f->f_mapping->a_ops->get_xip_mem))) {
 868                         fput(f);
 869                         f = ERR_PTR(-EINVAL);
 870                 }
 871         }
 872
 873         return f;
 874
 875 cleanup_all:
 876         fops_put(f->f_op);
 877         if (f->f_mode & FMODE_WRITE) {
 878                 put_write_access(inode);
 879                 if (!special_file(inode->i_mode)) {
 880                         /*
 881                          * We don't consider this a real
 882                          * mnt_want/drop_write() pair
 883                          * because it all happenend right
 884                          * here, so just reset the state.
 885                          */
 886                         file_reset_write(f);
 887                         mnt_drop_write(mnt);
 888                 }
 889         }
 890         file_kill(f);
 891         f->f_path.dentry = NULL;
 892         f->f_path.mnt = NULL;
 893 cleanup_file:
 894         put_filp(f);
 895         dput(dentry);
 896         mntput(mnt);
 897         return ERR_PTR(error);
 898 }
 899
 900 /**
 901  * lookup_instantiate_filp - instantiates the open intent filp
 902  * @nd: pointer to nameidata
 903  * @dentry: pointer to dentry
 904  * @open: open callback
 905  *
 906  * Helper for filesystems that want to use lookup open intents and pass back
 907  * a fully instantiated struct file to the caller.
 908  * This function is meant to be called from within a filesystem's
 909  * lookup method.
 910  * Beware of calling it for non-regular files! Those ->open methods might block
 911  * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo,
 912  * leading to a deadlock, as nobody can open that fifo anymore, because
 913  * another process to open fifo will block on locked parent when doing lookup).
 914  * Note that in case of error, nd->intent.open.file is destroyed, but the
 915  * path information remains valid.
 916  * If the open callback is set to NULL, then the standard f_op->open()
 917  * filesystem callback is substituted.
 918  */
 919 struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
 920                 int (*open)(struct inode *, struct file *))
 921 {
 922         const struct cred *cred = current_cred();
 923
 924         if (IS_ERR(nd->intent.open.file))
 925                 goto out;
 926         if (IS_ERR(dentry))
 927                 goto out_err;
 928         nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
 929                                              nd->intent.open.file,
 930                                              open, cred);
 931 out:
 932         return nd->intent.open.file;
 933 out_err:
 934         release_open_intent(nd);
 935         nd->intent.open.file = (struct file *)dentry;
 936         goto out;
 937 }
 938 EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
 939
 940 /**
 941  * nameidata_to_filp - convert a nameidata to an open filp.
 942  * @nd: pointer to nameidata
 943  * @flags: open flags
 944  *
 945  * Note that this function destroys the original nameidata
 946  */
 947 struct file *nameidata_to_filp(struct nameidata *nd)
 948 {
 949         const struct cred *cred = current_cred();
 950         struct file *filp;
 951
 952         /* Pick up the filp from the open intent */
 953         filp = nd->intent.open.file;
 954         /* Has the filesystem initialised the file for us? */
 955         if (filp->f_path.dentry == NULL)
 956                 filp = __dentry_open(nd->path.dentry, nd->path.mnt, filp,
 957                                      NULL, cred);
 958         else
 959                 path_put(&nd->path);
 960         return filp;
 961 }
 962
 963 /*
 964  * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
 965  * error.
 966  */
 967 struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
 968                          const struct cred *cred)
 969 {
 970         int error;
 971         struct file *f;
 972
 973         validate_creds(cred);
 974
 975         /*
 976          * We must always pass in a valid mount pointer.   Historically
 977          * callers got away with not passing it, but we must enforce this at
 978          * the earliest possible point now to avoid strange problems deep in the
 979          * filesystem stack.
 980          */
 981         if (!mnt) {
 982                 printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__);
 983                 dump_stack();
 984                 return ERR_PTR(-EINVAL);
 985         }
 986
 987         error = -ENFILE;
 988         f = get_empty_filp();
 989         if (f == NULL) {
 990                 dput(dentry);
 991                 mntput(mnt);
 992                 return ERR_PTR(error);
 993         }
 994
 995         f->f_flags = flags;
 996         return __dentry_open(dentry, mnt, f, NULL, cred);
 997 }
 998 EXPORT_SYMBOL(dentry_open);
 999
1000 static void __put_unused_fd(struct files_struct *files, unsigned int fd)
1001 {
1002         struct fdtable *fdt = files_fdtable(files);
1003         __FD_CLR(fd, fdt->open_fds);
1004         if (fd < files->next_fd)
1005                 files->next_fd = fd;
1006 }
1007
1008 void put_unused_fd(unsigned int fd)
1009 {
1010         struct files_struct *files = current->files;
1011         spin_lock(&files->file_lock);
1012         __put_unused_fd(files, fd);
1013         spin_unlock(&files->file_lock);
1014 }
1015
1016 EXPORT_SYMBOL(put_unused_fd);
1017
1018 /*
1019  * Install a file pointer in the fd array.
1020  *
1021  * The VFS is full of places where we drop the files lock between
1022  * setting the open_fds bitmap and installing the file in the file
1023  * array.  At any such point, we are vulnerable to a dup2() race
1024  * installing a file in the array before us.  We need to detect this and
1025  * fput() the struct file we are about to overwrite in this case.
1026  *
1027  * It should never happen - if we allow dup2() do it, _really_ bad things
1028  * will follow.
1029  */
1030
1031 void fd_install(unsigned int fd, struct file *file)
1032 {
1033         struct files_struct *files = current->files;
1034         struct fdtable *fdt;
1035         spin_lock(&files->file_lock);
1036         fdt = files_fdtable(files);
1037         BUG_ON(fdt->fd[fd] != NULL);
1038         rcu_assign_pointer(fdt->fd[fd], file);
1039         spin_unlock(&files->file_lock);
1040 }
1041
1042 EXPORT_SYMBOL(fd_install);
1043
1044 long do_sys_open(int dfd, const char __user *filename, int flags, int mode)
1045 {
1046         char *tmp = getname(filename);
1047         int fd = PTR_ERR(tmp);
1048
1049         if (!IS_ERR(tmp)) {
1050                 fd = get_unused_fd_flags(flags);
1051                 if (fd >= 0) {
1052                         struct file *f = do_filp_open(dfd, tmp, flags, mode, 0);
1053                         if (IS_ERR(f)) {
1054                                 put_unused_fd(fd);
1055                                 fd = PTR_ERR(f);
1056                         } else {
1057                                 fsnotify_open(f->f_path.dentry);
1058                                 fd_install(fd, f);
1059                         }
1060                 }
1061                 putname(tmp);
1062         }
1063         return fd;
1064 }
1065
1066 SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, int, mode)
1067 {
1068         long ret;
1069
1070         if (force_o_largefile())
1071                 flags |= O_LARGEFILE;
1072
1073         ret = do_sys_open(AT_FDCWD, filename, flags, mode);
1074         /* avoid REGPARM breakage on x86: */
1075         asmlinkage_protect(3, ret, filename, flags, mode);
1076         return ret;
1077 }
1078
1079 SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1080                 int, mode)
1081 {
1082         long ret;
1083
1084         if (force_o_largefile())
1085                 flags |= O_LARGEFILE;
1086
1087         ret = do_sys_open(dfd, filename, flags, mode);
1088         /* avoid REGPARM breakage on x86: */
1089         asmlinkage_protect(4, ret, dfd, filename, flags, mode);
1090         return ret;
1091 }
1092
1093 #ifndef __alpha__
1094
1095 /*
1096  * For backward compatibility?  Maybe this should be moved
1097  * into arch/i386 instead?
1098  */
1099 SYSCALL_DEFINE2(creat, const char __user *, pathname, int, mode)
1100 {
1101         return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
1102 }
1103
1104 #endif
1105
1106 /*
1107  * "id" is the POSIX thread ID. We use the
1108  * files pointer for this..
1109  */
1110 int filp_close(struct file *filp, fl_owner_t id)
1111 {
1112         int retval = 0;
1113
1114         if (!file_count(filp)) {
1115                 printk(KERN_ERR "VFS: Close: file count is 0\n");
1116                 return 0;
1117         }
1118
1119         if (filp->f_op && filp->f_op->flush)
1120                 retval = filp->f_op->flush(filp, id);
1121
1122         dnotify_flush(filp, id);
1123         locks_remove_posix(filp, id);
1124         fput(filp);
1125         return retval;
1126 }
1127
1128 EXPORT_SYMBOL(filp_close);
1129
1130 /*
1131  * Careful here! We test whether the file pointer is NULL before
1132  * releasing the fd. This ensures that one clone task can't release
1133  * an fd while another clone is opening it.
1134  */
1135 SYSCALL_DEFINE1(close, unsigned int, fd)
1136 {
1137         struct file * filp;
1138         struct files_struct *files = current->files;
1139         struct fdtable *fdt;
1140         int retval;
1141
1142         spin_lock(&files->file_lock);
1143         fdt = files_fdtable(files);
1144         if (fd >= fdt->max_fds)
1145                 goto out_unlock;
1146         filp = fdt->fd[fd];
1147         if (!filp)
1148                 goto out_unlock;
1149         rcu_assign_pointer(fdt->fd[fd], NULL);
1150         FD_CLR(fd, fdt->close_on_exec);
1151         __put_unused_fd(files, fd);
1152         spin_unlock(&files->file_lock);
1153         retval = filp_close(filp, files);
1154
1155         /* can't restart close syscall because file table entry was cleared */
1156         if (unlikely(retval == -ERESTARTSYS ||
1157                      retval == -ERESTARTNOINTR ||
1158                      retval == -ERESTARTNOHAND ||
1159                      retval == -ERESTART_RESTARTBLOCK))
1160                 retval = -EINTR;
1161
1162         return retval;
1163
1164 out_unlock:
1165         spin_unlock(&files->file_lock);
1166         return -EBADF;
1167 }
1168 EXPORT_SYMBOL(sys_close);
1169
1170 /*
1171  * This routine simulates a hangup on the tty, to arrange that users
1172  * are given clean terminals at login time.
1173  */
1174 SYSCALL_DEFINE0(vhangup)
1175 {
1176         if (capable(CAP_SYS_TTY_CONFIG)) {
1177                 tty_vhangup_self();
1178                 return 0;
1179         }
1180         return -EPERM;
1181 }
1182
1183 /*
1184  * Called when an inode is about to be open.
1185  * We use this to disallow opening large files on 32bit systems if
1186  * the caller didn't specify O_LARGEFILE.  On 64bit systems we force
1187  * on this flag in sys_open.
1188  */
1189 int generic_file_open(struct inode * inode, struct file * filp)
1190 {
1191         if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1192                 return -EOVERFLOW;
1193         return 0;
1194 }
1195
1196 EXPORT_SYMBOL(generic_file_open);
1197
1198 /*
1199  * This is used by subsystems that don't want seekable
1200  * file descriptors
1201  */
1202 int nonseekable_open(struct inode *inode, struct file *filp)
1203 {
1204         filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1205         return 0;
1206 }
1207
1208 EXPORT_SYMBOL(nonseekable_open);